Transmission Position Sensor/Switch: Testing and Inspection

Chart C-1A, Park/Neutral Switch Diagnosis:

Park/Neutral Switch Circuit Diagram:

CIRCUIT DESCRIPTION:

The PARK/NEUTRAL switch contacts are closed to ground in park or neutral and open in drive ranges. The ECM supplies ignition voltage through a current limiting resistor to circuit 434, and senses a closed switch when the voltage on circuit 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to control idle air and vehicle speed sensor diagnostics.


TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. Checks for a closed switch to ground in the park position. "SCAN" tool should indicate "Park/Neutral" condition. Different "SCAN" tools display P/N switch state differently. Refer to operating manual for specific tool used.

2. Checks for an open switch. With terminals jumpered together, "SCAN" tool should indicate "Park/Neutral" condition.

3. Checks for change of state in switch logic. If a change is indicated, switch and wiring are OK. If there was a problem, condition may be intermittent. Make sure correcty state is indicated, even while "wiggling" shifter.